Seems more reasonable to compare the typical initial cost vs the increased initial cost for the higher efficiency unit that saves $500/yr. My house was built i

Seems more reasonable to compare the typical initial cost vs the increased initial cost for the higher efficiency unit that saves $500/yr. My house was built in 2000 with a regular AC unit for the main floor and heat pump for the 2nd floor, both Payne, a builder grade of Carrier. The inside coil went first, at the 9-yr mark with a 10-yr warranty, so I did get a new coil at no expense but it cost $600 to install it. A couple years later, the outside heat pump went out, and because of the system's age (about 11 years), they recommended replacing the furnace and heat pump. A couple year later, the main floor furnace exhaust gas blower mechanism went out, and again, the outside unit was replaced because it was 14 years old. In contrast, my previous house had an American Standard AC and furnace that was installed in 1970 when the house was built. I had to replace the furnace blower motor one year - about $500 I think - but the original AC and furnace were working like a champ when I sold the house in 2003. In summary, you aren't getting 20 years out of any modern, shitty system anymore. They're designed to fail after 10 years. You might get lucky and have something fail after 9 years; then you'll only have to pay for labor. But because there are 2 major independent components, the outside compressor and inside furnace, it's unlikely they'll both fail within the warranty. My AC guy told me the main reason they fail is because the new coils are made of very thin aluminum and so fail sooner than the old systems. If a coil fails, either in the furnace or the outside condenser, you're screwed. They can sometimes fix them, but good luck with that. Most HVAC dealers don't want to bother doing that; they just want to sell a new system.